[Association of vitamin D deficiency with severity of symptoms in children with vasovagal syncope]

Objective: To investigate the correlation between vitamin D deficiency and the severity of symptoms in children with vasovagal syncope (VVS). Methods: A prospective study was conducted. One hundred and twenty-two children diagnosed with VVS by head up tilt test in Department of Pediatric Cardiology and 130 healthy children without symptoms who underwent physical examination in the outpatient department of Child Healthcare Department of Second Hospital of Lanzhou University from December 2019 to May 2021 were selected and assigned to VVS group and control group, respectively. According to the diagnostic criteria of vitamin D deficiency, children in the VVS group were assigned to three subgroups: non-vitamin D deficiency, vitamin D deficiency, and severe vitamin D deficiency. All children underwent detailed history taking, physical examination, and level determination of serum 25 (OH) D. Children in the VVS group were scored for orthostatic intolerance (OI) symptoms including 10 symptoms: syncope, dizziness, nausea, palpitation, headache, tremor, chest tightness, blurred vision, profuse perspiration, and attention deficit. The differences in the age, gender, body mass index, blood pressure, and serum 25 (OH) D levels between VVS group and control group, and the differences regarding the age, gender, body mass index, blood pressure, serum 25 (OH) D levels and symptom scores among the three VVS subgroups were compared. Comparisons were performed using independent sample t test, ANOVA analysis, Chi square test and rank sum test. Pearson correlation analysis was used to analyze the correlation between serum 25 (OH) D levels and OI symptom scores in children with VVS. Results: The serum 25 (OH) D levels were significantly lower in the VVS group than those in the control group ((31±11) vs. (46±10) nmol/L, t=10.89, P<0.001). Vitamin D deficiency was more frequent in the VVS group (73.0% (89/122) vs. 24.6% (32/130), χ²=58.91, P<0.001). There were significant differences among the severe vitamin D deficiency subgroup, vitamin D deficiency subgroup, and non-vitamin D deficiency subgroup regarding the serum 25 (OH) D levels ((9.8±0.4) vs. (26.6±6.5) vs. (45.8±5.9) nmol/L, F=142.77, P<0.001) and the OI symptom scores ((14±1) vs. (10±2) vs. (7±2) scores, F=44.97, P<0.001). The scores of syncope, nausea, profuse perspiration, blurred vision and dizziness among the severe vitamin D deficiency subgroup, vitamin D deficiency subgroup, and non-vitamin D deficiency subgroup were statistically significant (H=9.01, 7.52, 12.11, 7.07 and 9.54, respectively, all P<0.05). Pearson correlation analysis showed that the serum 25 (OH) D levels were negatively correlated with OI symptom scores in children with VVS (r=-0.769, P<0.001). Conclusions: VVS children have significant vitamin D deficiency. The severity of symptoms increases with decreasing of vitamin D level. Syncope, nausea, and profuse perspiration are more likely to occur in children with severe vitamin D deficiency, and dizziness and blurred vision are more likely to occur in children with vitamin D deficiency.

Non-destructive analysis on nano-textured surface of the vertical LED for light enhancement

In this work, the nano-textured surface of a GaN-based vertical light emitting diode (VLED) is characterized using a unified framework of non-destructive techniques (NDT) incorporating scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Photoluminescence (PL), and X-ray diffraction (XRD) to optimize the light output efficiency. The surface roughness of ∼300 nm is revealed by AFM. Compressive stress-state of 0.667 GPa in the GaN surface is indicated by the E₂(high) and A₁(LO) phonon peak values at 569 cm^-1 and 736 cm^-1, respectively, in Raman spectrum and the wavelength at 442 nm rather 450 nm in PL spectrum. Without damaging the LED, surface analysis by NDT helps to advance the understanding of the optimized angular light redistribution subject to the high-roughness surface and the negative impacts of the stress induced at the top GaN layer, which leads to the optical efficiency degradation of the VLED. Furthermore, the impact of texturing on underneath n-GaN and MQWs layers is investigated via SEM-based transmission Kikuchi diffraction (TKD) and aberration-corrected scanning transmission electron microscopy (AC-STEM) and revealed a smooth surface morphology and good crystalline quality, indicating that the etch-induced damage by texture engineering does not impair the active region of the VLED. Accordingly, prospective optimizations are suggested in the context of surface engineering for light enhancement in VLEDs.

Distributed optical signal processing for microwave photonics subsystems

We propose and experimentally demonstrate a novel and practical microwave photonic system that is capable of executing cascaded signal processing functions comprising a microwave photonic bandpass filter and a phase shifter, while providing separate and independent control for each function. The experimental results demonstrate a single bandpass microwave photonic filter with a 3-dB bandwidth of 15 MHz and an out-of-band ratio of over 40 dB, together with a simultaneous RF phase tuning control of 0-215° with less than ± 3 dB filter shape variance.

Drug delivery observation of hydrophobe ferrofluid and magnetite nanoparticals by SPring-8 synchrotron radiation

In this study, the composite magnetic nanoparticles of coated SiO nano film with about 8 nm size and high saturation magnetization value, were synthesized by liquid phase precipitation method. The magnetic nanoparticles can be dispersed in various liquid media, widely known as magnetic fluids or ferrofluids with both magnetic and liquid properties. The materials been collected great interests and more and more attentions to focus into Drug Delivery System (DDS) as a new technology in this paper. We use the composite nanoparticles to disperse H2O and inject the solutions into rat's in-vivo organs. And, in the experiments by using a strong photon beam of SPring-8 Synchrotron Radiation facility, the distribution stat and the effects of magnetic field as well as drug delivery behaviour of nanoparticles in the rat' kidney are verified by the in-vivo observations.